Reisong A10: Technical review.

[gadget73]

picture is correct. 9 will connect to one side of the heater supply, and the other will go to 4 or 5 depending on which side of the tube you are using. Ground the un-used pins.

Were this mine I'd alternate them so you can basically double the lifespan of the tubes. Triode 1 gets used on one, triode 2 on the other, and whenever they eventually wear out you can just flip them and get a whole un-used section to run.

 

[FlaCharlie]

I'm confused a bit. Which pin am I floating? Here's one side of amp example:

IMG_0407

• JohnLA
• Jan 4, 2022

12AX7 wiring one side

So the above example of one of the tubes, I am grounding only 6, 7, 8, and leaving 5 open? Other side tube I'd ground 1,2,3 and leave 4 open. Correct?

Yes.

The wire from Pin 9 of one tube would go to Pin 9 of the other tube and the wire from Pin 4 of one tube would go to Pin 5 of the second tube.

 

[JohnLA]

Yes.

The wire from Pin 9 of one tube would go to Pin 9 of the other tube and the wire from Pin 4 of one tube would go to Pin 5 of the second tube.

Cool! Yes, 9 to 9, and then I meant 4->5. Sorry, still working on first cup of coffee. =)

Cheers!

 

[Terry]

Right, this is a "further mod" I mentioned but didn't get into, trying to keep this mod as simple as possible. But yes you can totally heat "side A" of one tube and "side B" of the other, tie the unused pins to ground and swap the 12AX7 tubes when they wear out.

I will say I really like the sound I get from these cheap JJ EL34L tubes. I've tried a bunch of different 6CA7, KT77 etc and keep going back to these JJ tubes.

I have not tried the JJ EL34L tubes, but I do like very much the JJ 6CA7 tubes. With JJ it seems to be a hit or miss, either you get a really nice sounding tube, and they are consistently good for subsequent purchases, or you get crappy sounding tubes .

 

[Terry]

There are a couple of points here I agree with, and a couple I do not, so I will weigh in on this discussion. BTW, not sure what happened to my original account but I can't seem to log into it.

1) Running power tubes near max wattage dissipation doesn't always sound the best, there are many tubes I like how they sound better running at 80% of their max. And not every tube sounds best with the suggested load, that to me depends on the operating point. You just have to play with a tube until you get the sound you like. That said many do sound there best there, so it is a pick your poison situation, you have to design by ear first in my opinion.

2) Yeah most of these Chinese amps are poorly designed, and they claim things that are not true. So take your chances on buying one. But to be honest they seem to be a pretty good platform to make modifications on to get to sound much better. They didn't always use to be that way though now they seem much better. Odd how many of them are looking similar to many of the older Jadis amps.

3) Why are they using the 12AX7 in that amp design? I don't see how that amp needs that much gain in that stage to drive the power tube.

Terry

 

[StepheK]

There are a couple of points here I agree with, and a couple I do not, so I will weigh in on this discussion. BTW, not sure what happened to my original account but I can't seem to log into it.
1) Running power tubes near max wattage dissipation doesn't always sound the best, there are many tubes I like how they sound better running at 80% of their max. And not every tube sounds best with the suggested load, that to me depends on the operating point. You just have to play with a tube until you get the sound you like. That said many do sound there best there, so it is a pick your poison situation, you have to design by ear first in my opinion.

If you want to get the rated power out of an SE amp, you need to run the tubes pretty hard. What I posted was a starting point, with major improvements in both power and sound quality. People are welcome to toy around with different operating points, amounts of feedback etc. to see what they like. I actually did try a lower operating point on this amplifier as part of this project, and it lost a measurable amount of bass response and made less power with higher distortion. My personal 6SQ7/EL34 amp also sounded best running these JJ EL34L tubes hard. Given they cost $15, I'm not sweating it if they don't last forever. I'm not going to comment on tubes or amplifiers I haven't actually worked with.

I think they are using a 12AX7 to ensure the input sensitivity is high enough for non-standard sources people are likely to run this amp off of. The other reason is it's a popular, easily found tube. I do agree using both sides of a 12AX7 clearly wasn't needed or helpful! It sounds and measured MUCH better using only one side/triode.

 

[Terry]

If you want to get the rated power out of an SE amp, you need to run the tubes pretty hard. What I posted was a starting point, with major improvements in both power and sound quality. People are welcome to toy around with different operating points, amounts of feedback etc. to see what they like. I actually did try a lower operating point on this amplifier as part of this project, and it lost a measurable amount of bass response and made less power with higher distortion. My personal 6SQ7/EL34 amp also sounded best running these JJ EL34L tubes hard. Given they cost $15, I'm not sweating it if they don't last forever. I'm not going to comment on tubes or amplifiers I haven't actually worked with.

I think they are using a 12AX7 to ensure the input sensitivity is high enough for non-standard sources people are likely to run this amp off of. The other reason is it's a popular, easily found tube. I do agree using both sides of a 12AX7 clearly wasn't needed or helpful! It sounds and measured MUCH better using only one side/triode.

Well that is the thing, what sounds good is good. So I am running a single ended pentode amplifier, and I like the sound of SEP mode much better than triode, if you use local feedback loops(NOT GLOBAL). So I mess with g2 a lot. Running g2 at full wattage doesn't in fact rarely sounds as good as if you back off, sometimes way off. This does effect the wattage output as it does effect the current through the tube, but often you get a more relaxed sound, with a different(I am not going to give opinions on this one) soundstage, one to which I like more.

Now regarding driver stages running a tube closer to its max wattage I agree almost if not always sound better, they start to sound very raunchy at some point.

Also I am curious. I like high Gm drivers when I can use them, they sound cleaner and clearer to me with less noise, although I am not sure they measure that way. I just can't seem to get a 12ax7 to sound very good at all, unless I use very expensive NOS tubes. I have a stash of Telefunkin 12AX7's I love, but no new 12ax7 has sounded even decent to me. I personally think it is the most over used and over rated tube there is. I really should give them another chance though, but by comparison higher Gm tubes sound generally better than lower ones to me.

 

[JohnLA]

Mission accomplished. Here's my notes on doing the "Skunkie" mod for anyone interested. To start, here's my little setup/specs:

Pioneer PLX1000 turntable w/ VM540ML cart/stylus
Schiit Mani Phono Preamp
Reisong A10 w/GL Gen KT77s, 12AX7s, and U77/GZ34 tubes
Klipsch KG4 speakers w/Crites tweeters, and new crossovers built using Crites schematic, running on the A10s 4OHM posts
I have about 120 hours on tubes and stylus.

Mods now done to A10 are an earlier coupler cap swap for Russian PIOs, and now, the super "Skunkie" mod. =)

NOTES:

*I am not a sound engineer, electrical engineer, or even train engineer. I'm an average Joe who loves to listen to music. So my terms might not be "technical", lol.
Music: Classic jazz and vocals, mostly. But also get in my fill of rock, soul, and everything else.
Before the mod, I was happy with the sound of my A10, most of the time listening at lower volume levels in the evenings once kids are in bed.

AFTER THE SKUNKIE MOD, (plus I did the rewiring for 12AX7s):

1. LOUDER! First thing I immediately notice is that my usual late evening volume knob position (40%) is much louder than it was before.
2. LOUDER PART 2: And the increase continues around the volume dial. Before, the volume increase seemed to drop off after halfway around.
3. AIRY! There seems to be a lot more "air" or "live space" to the music, if that makes sense.
4. DYNAMIC: Probably goes with #3. Instrumentation is a LOT more detailed.
5. HIGHS: Pleasantly crisp and clear now.
6. BASS: At first, it seemed like I lost some low low end. BUT, I then realized that what I may have lost is "muddiness".
7. BASS PART 2: The DETAIL of the bass is now quite amazing. The "boom" has been replaced with clarity.
8. DRUMS: The biggest impact I noticed is drums. My God! What a difference! Every part of the kit is so much more "THERE".
9. SOUND STAGE: Given the previous notes, the gain in sound stage is expected, and delivers.
10. DEPTH: I guess this goes with previous note and the "airy"ness. It's like a pinch of reverb has been added, if that makes sense?
11. VOCALS: Another HUGE difference to my ears. I can hear much more expression in the vocals, crisp t's, s's, and breaths. Amazing.

Again, I was one of those who thought the A10 sounded great as it was, with just some better tubes in there. Apparently, I had no clue, lol.
Most definitely worth the $25 in parts and time spent doing the mod, as well as learning about all this stuff.
@StepheK - Thank you SO much for sharing and demonstrating. You rock so much!!!

ISSUES/TO DO:
Ok, so I have a hum now. Definitely sounds like a 60hz hum.
--Turntable/preamp off, the loudness of the hum does not increase if volume knob is rotated.
--Turntable/preamp on, the loudness of the hum lowers a tad as I increase volume, but a decent level of noise floor hiss gets turned up. That might have been there before, I just maybe never turned the amp all the way up before in this manner.

I am guessing that I have a not so good solder job in there somewhere. Any other ideas?

JG

 

[StepheK]

ISSUES/TO DO:
Ok, so I have a hum now. Definitely sounds like a 60hz hum.
--Turntable/preamp off, the loudness of the hum does not increase if volume knob is rotated.
--Turntable/preamp on, the loudness of the hum lowers a tad as I increase volume, but a decent level of noise floor hiss gets turned up. That might have been there before, I just maybe never turned the amp all the way up before in this manner.

I am guessing that I have a not so good solder job in there somewhere. Any other ideas?

JG

Given you rewired the driver tube heaters, I would suspect something in the "lead dress" to those tubes. Are the wires tightly twisted and away from any signal wiring?

 

[JohnLA]

Given you rewired the driver tube heaters, I would suspect something in the "lead dress" to those tubes. Are the wires tightly twisted and away from any signal wiring?

Ah! That could definitely be a possibility. In order to rewire for 12AX7 tubes, I had to untwist wires some in order to be able to reach the necessary pins. The heater wires that go from socket to socket were originally running up along corner, above the power and volume pots. They're not anymore.

So sounds like first step is to go grab some hookup wire and get back in there. =) Which is great, cause I'm kind of addicted to the smell of burning solder now, lol.

 

[gadget73]

if you use the right kind of solder it does actually smell nice. I'm somewhat partial to the piney smell that Kester rosin core makes.

 

[Lavane]

if you use the right kind of solder it does actually smell nice. I'm somewhat partial to the piney smell that Kester rosin core makes.

I had to remove some of that lead free solder a couple days ago. I do not like it.

 

[1cheesepasty]

Mission accomplished. Here's my notes on doing the "Skunkie" mod for anyone interested. To start, here's my little setup/specs:

Pioneer PLX1000 turntable w/ VM540ML cart/stylus
Schiit Mani Phono Preamp
Reisong A10 w/GL Gen KT77s, 12AX7s, and U77/GZ34 tubes
Klipsch KG4 speakers w/Crites tweeters, and new crossovers built using Crites schematic, running on the A10s 4OHM posts
I have about 120 hours on tubes and stylus.

Mods now done to A10 are an earlier coupler cap swap for Russian PIOs, and now, the super "Skunkie" mod. =)

NOTES:

*I am not a sound engineer, electrical engineer, or even train engineer. I'm an average Joe who loves to listen to music. So my terms might not be "technical", lol.
Music: Classic jazz and vocals, mostly. But also get in my fill of rock, soul, and everything else.
Before the mod, I was happy with the sound of my A10, most of the time listening at lower volume levels in the evenings once kids are in bed.

AFTER THE SKUNKIE MOD, (plus I did the rewiring for 12AX7s):

1. LOUDER! First thing I immediately notice is that my usual late evening volume knob position (40%) is much louder than it was before.
2. LOUDER PART 2: And the increase continues around the volume dial. Before, the volume increase seemed to drop off after halfway around.
3. AIRY! There seems to be a lot more "air" or "live space" to the music, if that makes sense.
4. DYNAMIC: Probably goes with #3. Instrumentation is a LOT more detailed.
5. HIGHS: Pleasantly crisp and clear now.
6. BASS: At first, it seemed like I lost some low low end. BUT, I then realized that what I may have lost is "muddiness".
7. BASS PART 2: The DETAIL of the bass is now quite amazing. The "boom" has been replaced with clarity.
8. DRUMS: The biggest impact I noticed is drums. My God! What a difference! Every part of the kit is so much more "THERE".
9. SOUND STAGE: Given the previous notes, the gain in sound stage is expected, and delivers.
10. DEPTH: I guess this goes with previous note and the "airy"ness. It's like a pinch of reverb has been added, if that makes sense?
11. VOCALS: Another HUGE difference to my ears. I can hear much more expression in the vocals, crisp t's, s's, and breaths. Amazing.

Again, I was one of those who thought the A10 sounded great as it was, with just some better tubes in there. Apparently, I had no clue, lol.
Most definitely worth the $25 in parts and time spent doing the mod, as well as learning about all this stuff.
@StepheK - Thank you SO much for sharing and demonstrating. You rock so much!!!

ISSUES/TO DO:
Ok, so I have a hum now. Definitely sounds like a 60hz hum.
--Turntable/preamp off, the loudness of the hum does not increase if volume knob is rotated.
--Turntable/preamp on, the loudness of the hum lowers a tad as I increase volume, but a decent level of noise floor hiss gets turned up. That might have been there before, I just maybe never turned the amp all the way up before in this manner.

I am guessing that I have a not so good solder job in there somewhere. Any other ideas?

JG

The potential of introducing hum is the one thing that's putting me off doing these mods. Apart from installing PIO coupling caps, my A10 is fairly standard. However, if I use 12AX7s with adapters instead of the original spec 6N2 tubes, a noticeable and annoying hum is apparent. Changing adapters makes no difference.

Hard wiring this hum into the amp by doing the mods isn't something that I'm keen on doing without understanding if the root cause can be addressed.

The issue of 12AX7 induced hum on A10s has been mentioned on other boards so it seems that my experience isn't isolated.

@StepheK - the above isn't intended as a criticism of the efforts you're putting in to improve the performance of this amp. You're doing a great job in helping to introduce a new generation of hifi enthusiasts into the joys of tube amp modification.

 

[JohnLA]

Given you rewired the driver tube heaters, I would suspect something in the "lead dress" to those tubes. Are the wires tightly twisted and away from any signal wiring?

UPDATE: Got under the hood today, and rewired the heater wires. Cleaned out old solder, used new wire. Did a good job winding the wires, and then fresh solder onto tube sockets. Tucked the wire up against the edge as was previously.

NO HUM! Sweet, Jesus. Sounds so good. Thanks again, @StepheK !!!

 

[Rx4Pain]

I'm late to this party, but I recently ordered the Reisong A12.

I have not logged on here for a couple years, but seeing StepheK's work both here and on YouTube inspired me to come say Thank You!
What a generous soul you are Stephe! Competent...And, I like that you say it like it is! lol.

I have already picked up a couple of 6v6 tubes, that I will run just to see the direction this amp will take...prior to obtaining the parts/doing the work as StepheK outlined previously.
My question is, since I know I will want to run this thing and have a listen when I get it...other than swapping out to the 6v6 tubes, is there anything else one can do without cracking the thing open, to improve the listening, before jumping in to complete the mods?
Rectifier tube for example???

Ken

 

[Old Guy8]

I'm late to this party, but I recently ordered the Reisong A12.

I have not logged on here for a couple years, but seeing StepheK's work both here and on YouTube inspired me to come say Thank You!
What a generous soul you are Stephe! Competent...And, I like that you say it like it is! lol.

I have already picked up a couple of 6v6 tubes, that I will run just to see the direction this amp will take...prior to obtaining the parts/doing the work as StepheK outlined previously.
My question is, since I know I will want to run this thing and have a listen when I get it...other than swapping out to the 6v6 tubes, is there anything else one can do without cracking the thing open, to improve the listening, before jumping in to complete the mods?
Rectifier tube for example???

Ken

Edit: My error. I have an A10, with different spec input tubes. You have an A12. (So disregard this. I use NOS Soviet Voskhod Rocket 6N2P-EV/EB silver shield tubes. They were an improvement over the glassy stock Chinese input tubes. I bought from VivaTubes.com I believe. They were cheap.)

I'm also now using NOS Tungsol vintage USA 6V6GT Gray Plate Repaired base tubes I got from Viva Tubes. A little pricey. Stock Chinese Rectifier as Stephe recommended in this thread.
With 4 ohm tapes. 8 ohm Canton Karat 200 speakers through High Level speaker connections from a HT subwoofer. To reinforce weak bass.

IMO, it is improved over stock.

If you have some other 12ax7 tubes you could try. Now I'm guessing, not having an A12. My Boyuurange A50 300b amp also responded well to replacing stock Chinese input tubes with NOS.

 

[1cheesepasty]

Edit: My error. I have an A10, with different spec input tubes. You have an A12. (So disregard this. I use NOS Soviet Voskhod Rocket 6N2P-EV/EB silver shield tubes. They were an improvement over the glassy stock Chinese input tubes. I bought from VivaTubes.com I believe. They were cheap.)

I'm also now using NOS Tungsol vintage USA 6V6GT Gray Plate Repaired base tubes I got from Viva Tubes. A little pricey. Stock Chinese Rectifier as Stephe recommended in this thread.
With 4 ohm tapes. 8 ohm Canton Karat 200 speakers . High level speaker connection to a HT subwoofer. To reinforce weak bass.

IMO, it is improved over stock.

If you have some other 12ax7 tubes you could try. Now I'm guessing, not having an A12.

I'm currently running my A10 with a very similar setup. In my case, Russian 6V6GTs, stock rectifier, 4ohm speaker outputs to subwoofer then out to B&W DM601S2 speakers.

I also use a Bluetooth tube preamp (Douk P1) both as a streaming feed and also to provide tone controls.

Although I've not done the StepheK mods yet, I have swapped out the standard coupling caps for Miflex KPCU-01 0.22uF 600v. That made a huge difference for less than £30.

 

[StepheK]

The potential of introducing hum is the one thing that's putting me off doing these mods. Apart from installing PIO coupling caps, my A10 is fairly standard. However, if I use 12AX7s with adapters instead of the original spec 6N2 tubes, a noticeable and annoying hum is apparent. Changing adapters makes no difference.

Hard wiring this hum into the amp by doing the mods isn't something that I'm keen on doing without understanding if the root cause can be addressed.

The issue of 12AX7 induced hum on A10s has been mentioned on other boards so it seems that my experience isn't isolated.

@StepheK - the above isn't intended as a criticism of the efforts you're putting in to improve the performance of this amp. You're doing a great job in helping to introduce a new generation of hifi enthusiasts into the joys of tube amp modification.

It's the adapter having to cross the heater leads across the signal leads causing this hum. As noted by another poster in this thread, lead dress (twisting the AC heater wires and keeping them away from the signal/grid) is vital.

 

[Rx4Pain]

Old Guy, thank you for the thoughts/suggestions. I have been into Audio and the like, since the mid 70's. The products, the music formats, the arguments, the hype. All of it

I have the A 12 set up and really did it in the worst possible way....if trying to get a feel for how this little amp "sounds".
I have a solid state set up for my home office (10 x 11 room), that has my speakers (Old Yamaha NX-E150's that I have always liked/came with the CRX E150 mini system years ago) and a Monoprice 8 inch sub to round out the sound.
Now I would usually introduce the A 12 into that setup, as it is completely dialed in...and I use it for my music, CD's, FLAC Conversion, a 70's Turntable , H4N Recordings of the Piano that is also in my Office etc etc. Point being...I know the speakers and the sound.
It is to my liking, which is the warmer side of neutral.

The problem is, I did not want to rewire stuff and cable the things I already have established in the room. IE...Laziness.

So, I made room, and put the A 12 on its own stand, purchased two speaker stands and two budget speakers that I am NOT familiar with. (Fluance SX6's...yes I went cheap, relatively efficient without horns and relatively unknown) Yep. I know all the problems that introduces into having a listen to a new Amp.
I will likely end up getting a pair of used Pioneer B22's as I like their sound signature. That is another story.

I have a bit of break in on the speakers, but not what I would consider "Enough".

Ok, did I cover all the stuff that will get picked apart...I think so.

I started with the 6v6's in the Amp first. I wanted the best chance of "clean" listening, and took advantage of StepheK's observations...prompting this initial tube swap.

I listened to the A 12 using FLAC files from the CD's I accumulated during the 80's and 90's. At first, mostly Vocals. Melody Gardot, Frank Sinatra, Linda Rhondstat, Nora Jones, Gordon Lightfoot etc etc.
I thought it sounded smooth and clean enough, but it sounded rather "clinical" for lack of a better word. Un-colored. It did not provide what I had imagined. That could simply be...my imaginings were off, as it has been decades since I have listened to "tubes".
The volume was at 12 o'clock.

I swapped the 6v6's out...and installed the EL 84's that came with the amp. Instantly warmer to my ears, and appeared to have more "body" listening to the same songs. I admit, it might be the distortion that StepheK found...that was "filling out" the sound, giving it the body I prefer?
I am just getting into listening to this A 12. It is the very start of my listening, but I wanted to post it here, for the person looking for information and anecdotal accounts of the Reisong Products.

As I am posting this, I am listening to what I have always considered a well produced/recorded CD....Dire Straights "Brothers In Arms" (The first "DDD" CD I ever owned/listened to) It sounds amazingly clear, with good body and a pretty well balanced sound. I like what appears to be a bit of "room space" as I listen. And, the placement of instruments and vocal, seems quite "open". Better than my solid state set up? I don't know. But, it sounds nice.
Could just be my mind playing tricks on me. Wanted to mention it regardless.

I don't want this thing to sound clinical and "solid state-ish"....but I want to heed the experience of people like StepheK. So, we will see what I do in the future. My intent is to order the parts necessary and "clean it up" sonically, by following Stephek's mods.

I will update my thoughts as this unfolds. Thanks for the Thread and all the thoughts everyone.

 

[Old Guy8]

Old Guy, thank you for the thoughts/suggestions. I have been into Audio and the like, since the mid 70's. The products, the music formats, the arguments, the hype. All of it

I have the A 12 set up and really did it in the worst possible way....if trying to get a feel for how this little amp "sounds".
I have a solid state set up for my home office (10 x 11 room), that has my speakers (Old Yamaha NX-E150's that I have always liked/came with the CRX E150 mini system years ago) and a Monoprice 8 inch sub to round out the sound.
Now I would usually introduce the A 12 into that setup, as it is completely dialed in...and I use it for my music, CD's, FLAC Conversion, a 70's Turntable , H4N Recordings of the Piano that is also in my Office etc etc. Point being...I know the speakers and the sound.
It is to my liking, which is the warmer side of neutral.

The problem is, I did not want to rewire stuff and cable the things I already have established in the room. IE...Laziness.

So, I made room, and put the A 12 on its own stand, purchased two speaker stands and two budget speakers that I am NOT familiar with. (Fluance SX6's...yes I went cheap, relatively efficient without horns and relatively unknown) Yep. I know all the problems that introduces into having a listen to a new Amp.
I will likely end up getting a pair of used Pioneer B22's as I like their sound signature. That is another story.

I have a bit of break in on the speakers, but not what I would consider "Enough".

Ok, did I cover all the stuff that will get picked apart...I think so.

I started with the 6v6's in the Amp first. I wanted the best chance of "clean" listening, and took advantage of StepheK's observations...prompting this initial tube swap.

I listened to the A 12 using FLAC files from the CD's I accumulated during the 80's and 90's. At first, mostly Vocals. Melody Gardot, Frank Sinatra, Linda Rhondstat, Nora Jones, Gordon Lightfoot etc etc.
I thought it sounded smooth and clean enough, but it sounded rather "clinical" for lack of a better word. Un-colored. It did not provide what I had imagined. That could simply be...my imaginings were off, as it has been decades since I have listened to "tubes".
The volume was at 12 o'clock.

I swapped the 6v6's out...and installed the EL 84's that came with the amp. Instantly warmer to my ears, and appeared to have more "body" listening to the same songs. I admit, it might be the distortion that StepheK found...that was "filling out" the sound, giving it the body I prefer?
I am just getting into listening to this A 12. It is the very start of my listening, but I wanted to post it here, for the person looking for information and anecdotal accounts of the Reisong Products.

I don't want this thing to sound clinical and "solid state-ish"....but I want to heed the experience of people like StepheK. So, we will see what I do in the future. My intent is to order the parts necessary and "clean it up" sonically, by following Stephek's mods.

I will update my thoughts as this unfolds. Thanks for the Thread and all the thoughts everyone.

Everyone's ears and systems are different. My experience with my A10, once the Chinese input and output tubes were replaced with better tubes. I wouldn't describe as solid state like.
I'm currently using Soviet input tubes, 6V6 output tubes and a sub. Sounds much better than it did as stock.
Enjoy your new amp.